The present invention relates generally to a work holding chuck assembly for use in high speed machining applications, and more specifically to an equalizing chuck assembly including multiple sets of rocker arms having a jaw support located at one end and a counterweight located at an opposite end therefrom. A centrally-located axially moveable actuator is operably coupled to the rocker arms by an equalizer plate and a toggle link such that the equalizer plate moves the toggle link to rotate the rocker arm, thereby positioning the jaw supports radially inwardly and outwardly.
An adjustable chuck of the type in widespread use for gripping workpieces of different sizes typically includes a number of internal moving parts which serve to open and close the gripping jaws. Smooth operation of these parts is most important to assure that a positive clamping of the workpiece is achieved when the jaws are closed, and further that each of the jaws applies equal pressure against a workpiece to prevent distortion and possible eccentric location of the workpiece.
There has been a recent trend to require power chucks to operate at significantly higher rotational speeds. As such, the rotational balance of the chuck and the workpiece held within the chuck becomes increasingly important. At the speeds at which many chucks are used in modern manufacturing processes, even slight eccentricities or out of balance is unwanted. For example, an imbalance may cause improper machining which results in rejection of the workpiece. Alternately, an imbalance may create a change in the gripping force as a result of the centrifugal force created by the rotation of the jaw supports. Thus, it is desirable to provide a chuck which maintains a proper balance and constant gripping force independent of rotational speed in which is readily adjustable to insure concentric alignment with the machine tool.
The present invention provides a six jaw counter-centrifugal rocker arm chuck assembly for use in either ID or OD chucking applications. The chuck assembly includes multiple rocker arms pivotally coupled to the chuck housing. Each rocker arm has a jaw member disposed on one end and a counterweight disposed on the opposite end. An actuator is supported for axially movement in the chuck housing. Equalizing plates are coupled to the actuator for concurrent axial movement therewith, while permitting a degree of rotational freedom or yaw within the chuck housing. A toggle link interconnects each of the rock arms to an associated equalizing plate such that axial movement of the actuator pivots the rocker arms thereby moving the jaw members between an open position and a closed position. Yawing motion of the equalizing plates moves the rocker arms relative to one another to accommodate eccentricities in the workpiece.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicting the preferred embodiment of the invention, are intended for purposes of illustration only and not intended to limit the scope of the invention.